This invention relates generally to the collection and infusion of patient fluids, more specifically, to an assembly for coupling a catheter or other flexible tubular device with a retractable cannula/needle assembly. The retracting tip assembly includes two telescoping barrels and a collet which operate to automatically retract the needle into the interior of the barrels.
Many medicaments and fluids are routinely infused and discharged fluids collected through a catheter system connected to the patient and an administration container or a collection container. The typical administration set has a pre-filled plastic bag or bottle connected to one end of a catheter. The catheter may be integrally formed with the bag or the bag may have a puncturable port for connection with a needle on one end of the catheter. The other end of the catheter usually has a needle/cannula for insertion into the patient intravenously or enterally.
Collection bags or containers are constructed much the same way, except that the bag or container is initially empty. To infuse or collect from a patient, the needle/cannula at the free end of the catheter is inserted through the dermal layer into the lumen of the blood vessel and taps in to the circulation system of a patient or into other parts of the body. The catheter may have a clamp or valve which is manipulated to open the passageway from the bag to the patient. Once the infusion bag is empty or the collection bag full, each may be disconnected from the patient.
Some patients may require more than one container to be used during the treatment. In such cases, a catheter or port may be placed into the body by a cannula. Initially, the cannula is inserted through the skin to the desired location then the catheter may be inserted through the cannula and the cannula is thereafter removed leaving the port and/or catheter in place. Alternatively, the catheter may be fitted over the cannula with the point of the cannula extended beyond the end of the catheter. After the cannula is inserted in the patient, it is withdrawn from the catheter leaving the catheter in place.
The retractable cannula assembly with its contaminated needle presents the danger of an inadvertent needle stick to personnel handling the used equipment. Even trace amounts of body fluids from a person with Hepatitis, Acquired Immune Deficiency Syndrome (AIDS), and other infectious diseases, transferred into another""s blood stream can transmit these diseases. Thus, what is needed in the art is a needle/cannula assembly that protects from inadvertent needle sticks.
A retracting tip for a catheter set has telescoping barrels and a spring loaded cannula. Telescoping of the barrels into each other releases the spring compression on the cannula and results in the cannula being withdrawn into the barrels. The forward end of the inner barrel is telescoped into one end of a tubular outer barrel, the other end of the outer barrel has a restricted opening. The forward end of the inner barrel is formed with an enlarged circumferential ring and carries a resiliently expandable tubular collet engaging the restricted opening. The collet has a portion extending through the restricted opening of the outer barrel and that portion of the collet has an expanded dimension greater than the restricted opening. A tubular cannula holder is inserted through the collet with one end of the cannula holder extending through the collet and having a connection for removably attaching to a cannula. The cannula holder has a shoulder trap adjacent to the connection with the other end of said cannula holder disposed in the forward end of the inner barrel. The end of the cannula holder is formed with an enlarged flange. A first resilient spring is disposed in the outer barrel about said restricted opening with said spring engaging the circumferential ring of the inner barrel and urging the cannula holder toward the outer barrel. A shoulder trap on the cannula holder engages the portion of the collet thereby wedging the collet in the restricted opening. A second spring is disposed in the inner barrel about the cannula holder and engages the enlarged flange thereby urging the cannula holder into the inner barrel.
An objective of this invention is to provide a needle assembly having a catheter telescoped over the needle whereby the catheter remains in the patient after the needle is withdrawn from the patient.
An objective of the instant invention is to provide a needle assembly that causes the contaminated hypodermic cannula to retract into the assembly so that the needle is no longer exposed for accidental needle sticks. The retraction of the needle is automatically accomplished by the telescoping movement of one barrel into another barrel by activating a spring release mechanism.
It is a further objective of the instant invention to provide a retracting assembly that is attached to the cannula such that it does not interfere with the operation of the catheter set but is easily accessible for retraction of the needle.
Another objective of the instant invention is to provide a collet which expands and releases a spring biased needle retractor in response to the forward movement of the telescoping barrel. The forward end of the outer barrel carries a wedge which insures the collet fingers will spread apart upon forward movement of the collet.
A further object of this invention is to provide a catheter hub removably mounted over the collet fingers such that spreading apart of the fingers dislodges the catheter from the collet.
It is still another objective to provide an inexpensive, easily manufactured and used retracting needle assembly with a retractable needle mechanism for safe disposal and prevention of diseases.
Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate objects and features thereof.